Apparatus for braking a thread



NOV- 19, 1957 v. svATY' ET AL APPARATUS FOR BRAKNG A THREAD Filed Dec.8. 1954 United States. Patent() APPARATUS FOR BRAIQNG A THREAD VladimrSvaty and Lubomr Tatek, Liberec, Czechoslovakia, assignors to Mira,zavody na pletene a s tavkove zbozi, narodni podnik, Prague,Czechoslovakia Application December 8, 1954, Serial No. 473,920

3 Claims. (Cl. 242-151) 'I'he present invention relates to a method andan apparatus for braking a yarn or thread in a textile machine.

The braking of a yarn or thread in a textile machine may be accomplisheddirectly, that is, by subjecting the thread to friction produced eitherby winding the yarn or thread around a yarn guide or by guiding thethread or yarn between two surfaces of brake discs pressed against eachother, or indirectly bypassing a clamped or retained yarn or threadthrough rotary means, for instance, between a pair of rollers, braked ina suitable way.

The indirect braking action is unsuitable for a fluctuating velocity ofthe thread or yarn in View of the considerable inertia mass of thebraking members.

The direct braking action, by winding the thread or yarn around a yarnguide, causes the initial tension of the thread, wound oi a bobbin, tobe increased and is therefore suitable for uniform materials only wherethe tension of the thread wound off a bobbin is not subject toiluctuations.

The most common braking means used are braking discs which, however, areobjectionable because of the great inertia mass of the discs, which hasan unfavorable effect on the operation of the apparatus whenever a knotpasses between the discs, and also on account of an easy clogging of thebraking mechanism when a yarn containing impurities is used, and stillfurther because of considerable variations of the tension produced byone disc of the braking mechanism.

It has already been suggested to remove the above referred to drawbacksby the use of multiple brakes with a positive movement of the discs. Thebraking effect of every individual brake may in this way be reduced asmany times as corresponds to the number of the brakes used, and also thefluctuations of the total braking eiect may thus be reduced, but thisprocess is uneconomical.

Braking devices are also known wherein the thread is braked by thesliding and rolling friction resulting from Contact with a member ofindependent braking elements, for example, rollers or balls. Generally,such rollers or balls are arranged over the thread and gravitationallyurged into contact with the latter. However, in that case there is nopossibility for automatically removing, during operation, thoseimpurities carried by the thread which eventually clog the spacesbetween the balls or rollers. Further, since the effect of gravity isrelied upon for the braking of the thread, an adequate braking force canonly be obtained through the use of relatively heavy braking elements,and such heavy elements produce severe shocks and stresses when knots orthickened areas of the thread are encountered. Further, the gravityinuenced balls or rollers do not respond sensitively to variations inthe thickness of the thread and, therefore, produce a nonuniformbraking. In those cases where springs are employed to urge the balls orrollers against the braked thread, it is diicult to attain a precisesetting of the springs, while the braking action or force increases withthe dellection of the balls or rollers by the passage of a knot orthickened portion of the thread and frequently causes thread-breakage.

The known drawbacks are eliminated according to the present invention bybraking the thread or yarn by sliding and rolling 'friction in aplurality of points of contact independent from each other, using adevice which according to the invention consists of a braking disc and aplurality of braking rollers attracted to the braking disc by means of amagnet. The resulting braking effect represents the sum total of aplurality of partial values so as to reduce the uctuations of thetension of the thread to a minimum.

The accompanying drawing represents by way of example one embodiment ofthe apparatus according to the invention.

Fig. 1 is a side view of the apparatus of the invention, with partsbroken away; and

Fig. 2 is a partly sectioned plan View, the section being taken in theplane of the line 2 2 of Fig. 1.

The braking disc 1 made of non-magnetic metal is mounted for rotation ona pivot 2 secured in a holder 3. A side member 4 made of antimagneticmaterial, for instance, fibers, is secured to the pivot 2, said sidemember 4 carrying another side member 6 connected thereto by bolts S and5. Steel braking rollers 8 are located in grooves 7, 7 of the sidemembers 4 and 6, which rollers are provided with flanges 9 and biassedagainst the braking disc 1 by means of a permanent magnet 10 mounted inthe interior of the disc 1 and secured to the side member 4 by a screw11. The screw 11 is adjustable in a groove 11 of the side member 4, thuspermitting the adjustment of the position of the magnet 10 and in thisway also of the braking effect.

The rollers 8 are secured against falling out by a loop 12 of steelwire.

Yarn guides 13, 13 are provided on the bolts 5, 5.

The thread or yarn N is wound oi the bobbin 14, guided through the yarnguide 13 between the disc l and the rollers 8 and passed through theyarn guide 13 in the direction of the arrow S, for instance, to thewindingo and gauging device of a nozzle-operated weaving loom, not shownin the drawing.

The magnet 10 attracts the rollers 8 which press the thread N againstthe disc 1. When pulling the thread or yarn braked in this way, therollers 8 and the disc 1 are set in rotation, thus preventing anyclogging of the braking mechanism. The passage of knots is facilitatednot only by the possibility of rotation of the rollers 8 and their smallinertia mass but also by the fact that, on lifting a roller 8 by a knot,the distance of the roller from the magnet 10 is increased and thebraking eifect reduced, just contrary to spring-operated braking devicesin which upon passage of a knot the braking effect is increased, whichusually causes the thread to break.

The intensity of the braking effect may be adjusted by the number ofrollers 8 and by the change of the distance of the magnet 10 from thesurface of the disc 1.

The braking rollers 8 placed next to each other form a grate, whichallows the retained impurities to fall through.

We claim:

1. An apparatus for braking a thread, comprising a rotatable brakingdisc, two side members, one at each side of the braking disc, a seriesof radial grooves in both side members extending radially from outsideto a point beyond the circumference of the braking disc, a plurality ofmagnetic braking rollers mounted in said grooves for rotation about axesparallel to the axis of rotation of said disc and in contact with thecircumference of the braking disc, a retaining member preventingradially outward removal of the rollers from said grooves, and a magnetmounted in the interior of the braking disc and e f 21,813,683v t v l fmagnetically urging said rollers radially inward against l thecircumference of the braking disc, said magnet being adjustable radiallywith respect to said disc so as to change the attractive force exertedupon the rollers.

2. A device for braking a thread comprising anonmagnetic disc freelyrotatable about a horizontal't axis, ixed members at opposite sides offAsaid disc, having aligned series of groovesextending radially outwardfrom the periphery of said disc along a segmental portion of' saidperiphery disposed below said axis of rotation of the disc, a pluralityof magnetic rollers rotatably mounted in said grooves with their axesof. rotation parallel to said axis of the disc and being movableradially in said grooves toward and away from theperiphery of said disc,and a magnet within said disc acting through the periphery of the latterupon said rollers and magnetically urging the latter radially inwardagainst said periphery of the disc so that a thread running between saidperiphery and said rollers is braked by frictional and rolling contacttherewith.

3. A device as in claim 2; wherein one of said fixed members has a slottherein extending radially with respect to said disc, and furthercomprising support means for said magnet movable along said slot to varythe proximity of said magnet to said rollers and to correspondinglyadjust the force with which the latter are urged against said peripheryof the disc.

References Cited in the le of this patent UNITED STATES PATENTS1,055,108 Wells Mar. 4, 1913 1,441,544 Taylor et al. Jan. 9, 19231,675,330 Byrd July 3, 1928 2,614,773 Ammerall Oct. 21, 1952 2,650,043Grein Aug. 25, 1953 2,677,511 Bley May 4, 1954

